Study: Mutated H7N9 virus can pass more easily

Researchers note airborne transmission; official says risk to humans unchanged

A veterinary institute in China has found that the H7N9 bird flu virus has mutated, making the infection of animals significantly easier, but a Chinese health official said the mutation will not increase the risk of human-to-human transmission.

It took researchers at the Chinese Academy of Agricultural Sciences' Harbin Veterinary Research Institute nearly four years to complete their work, which included collecting more than 110,000 samples at live poultry markets, farms and slaughterhouses in most provinces.